<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>01_JS回顾</title>
</head>
<body>
<script>
    var a = 10;
    var b = 2.2;
    var c = "hello";
    var c2 = 'hello';
    var d = true;
    var e = false;
    var f;
    console.log(a,typeof a);
    console.log(b,typeof b);
    console.log(c,typeof c);
    console.log(c2,typeof c2);
    console.log(d,typeof d);
    console.log(e ,typeof e);
    console.log(f,typeof f);

    let obj = {};
    console.log(obj,typeof obj);
    obj.like="过新年";
    console.log(obj,typeof obj,obj.like);

    let arr = [1,true,"hello"];
    console.log(arr,typeof arr);
    console.log(arr[0],arr[1],arr[2],arr[99]);

    console.log(Number('23'),typeof Number('23'));
    console.log(Number(true),typeof Number(true));
    console.log(Number(false),typeof Number(false));
    console.log(Number('哈哈哈'),typeof Number('哈哈哈'));
    console.log(Number('7a'),typeof Number('7a'));

    console.log(Boolean(0));
    console.log(Boolean(null));
    console.log(Boolean(''));
    console.log(Boolean(NaN));
    console.log(Boolean(undefined));
    console.log(Boolean(' '));
    console.log(Boolean('下午好'));
    console.log(Boolean(666));

    let x=1;
    let y=true;
    console.log(x==y);
    console.log(x===y);
    console.log(3>7);
    console.log(3>'7');
    console.log('3'>'7');
    console.log('3'.charCodeAt());
    console.log('7'.charCodeAt());

</script>
</body>
</html>